Getting started

Regular vacuum cleaners remove loose dirt, but they hardly touch the dirt and oils that stick to carpet fibers. Carpet cleaners are supposed to go a step further: They typically spray on a detergent, sometimes working it in with moving brushes then vacuum up the dirty solution.

A machine's effectiveness depends in part on how aggressively it scrubs to loosen dirt and how powerfully its suction pulls dirt in. But too much aggressiveness could damage carpeting. (Powerful suction doesn't pose such a problem.) Some of the machines we've tested don't get at dirt at the bottom of a carpet, but instead remove mainly what you see near the surface.

Types

Homeowners who only occasionally clean their carpets may choose to hire a reputable professional or rent a carpet cleaner. But if you have a lot of carpeting and a house full of kids and pets, you might want to consider buying a machine. Here are the types of carpet cleaners to consider.

Often available at a nearby supermarket, hardware store or home center for about $20 to $30  a day, these upright machines combine a tank for dispensing cleaning solution, a second tank for holding dirty solution, a vacuum, and a fixed or moving brush into a single, heavy unit. As a result, they're cumbersome to push around. Performance and convenience vary from one machine to the next. In general, look for the cleanest, least-worn brushes on any machine that you're thinking of renting.

They’re lighter and less bulky than typical rental machines. Most work by scrubbing in a solution of water and detergent, then vacuuming up the water and dirt. The can be  expensive and take up a fair amount of broom-closet space. In our last tests, they produced mixed results. All those that we tested also required you to use the manufacturer's special detergent.

For small jobs or tackling stains a compact cleaner is easier to maneuver than the bigger and bulkier full-sized model, and it takes up less closet space and can be stored on a shelf. One compact, the Bisell SpotBot, allows you to push a button and walk away while it goes to work on stains. In our tests it removed the toughest stain from carpet treated with stain protector, but didn’t do as well on untreated carpet. Bissell’s $80 Little Green compact cleaner didn’t clean as well as most of the full-sized models we tested and did little on tough stains.

Features

Carpet cleaners can be a bit unwieldy, so look for features that will make it easier to maneuver, especially if you have carpeted stairs. Here are the carpet cleaner features to consider.

On upright models, they let you clean upholstery, stairs, bare floors, and tight spots between furniture.

As with vacuum cleaners, many carpet cleaners have a belt that, over time, needs replacing—a DIY task for some owners. Belt-free units dispense with this part.

A moving brush tends to give a more aggressive scrub than no brush or a fixed one that moves only as you push the machine, though having one or more does not guarantee good cleaning.

The larger the cleaning-solution tank, the less often you'll need to refill it if you clean a lot of carpet at a time—though the more liquid, the tougher the machine can be to maneuver.

The heavier the cleaner, the harder it is to maneuver. A long vacuum hose can reach, for example, up a flight of stairs.

This automatically dispenses the right amount of detergent with water, and shuts off to allow rinsing with fresh water.

These lights alert you when the clean-solution tank needs refilling—or the dirty-solution tank needs emptying.

Some cleaners feature a sensor-operated cutoff that stops an extractor's suction when the tank storing dirty solution is full.